1. Field of the Invention
The present invention relates to an ink-jet recording apparatus, and an ink-temperature control method in the same. More particularly, the invention relates to ink-temperature control in an ink-jet recording apparatus, which performs recording by causing an ink-jet recording head, for performing recording by discharging ink, to perform scanning on a recording medium.
2. Description of the Related Art
Printers that record information including desired characters, images and the like, on a sheet-shaped recording medium, such as paper, a film or the like, are widely being used as information output apparatuses in word processors, personal computers, facsimile apparatuses and the like.
Various recording methods for printers are known. Recently, attention is particularly paid to an ink-jet method, because, for example, non-contact recording can be performed on a recording medium, such as paper or the like, color printing can be easily performed, and silent printing can be performed. As for the configuration of ink-jet recording, a serial recording method, in which recording is performed by mounting a recording head for discharging ink in accordance with desired recording information and performing reciprocating scanning in directions orthogonal to a direction of feeding a recording medium, such as paper or the like, is being widely used because, for example, an inexpensive and small-size printer can be easily obtained.
Generally, the viscosity of ink used in ink-jet recording apparatuses increases in a low-temperature environment. As a result, in a low-temperature environment, phenomena such that the volume of ink discharged from a recording head decreases (variations in the amount of ink discharge), and normal ink discharge is not performed (a failure in ink discharge) occur.
In such a case, for example, unevenness in the density due to variations in the amount of ink discharge, and incomplete dot shapes due to a failure in ink discharge are observed in a recorded image, thereby greatly degrading the quality of recording.
Furthermore, if a volatile ink component evaporates in an ink channel provided near a discharge port of a recording head to increase the viscosity of ink, a failure in ink discharge tends to occur even after a few ink discharging operations.
In order to solve such variations in the amount of ink discharge and a failure in ink discharge, in conventional ink-jet recording apparatuses, control is performed by heating a recording head so that the temperature of the recording head is within a predetermined temperature range, before or during a recording operation.
The following two methods for heating a recording head are present. In a short-pulse heating method, discharge heaters for discharging ink droplets are heated with a pulse so short as not to cause ink discharge. In a sub-heater heating method, ink is directly or indirectly heated by providing a heat-retaining sub-heater separately from discharge heaters.
In any of the above-described methods, as a general temperature control sequence, short-pulse heating or sub-heater heating is performed until the temperature of the recording head reaches a target temperature, and heating is interrupted when the temperature of the recording head exceeds the target temperature.
However, the methods for controlling the temperature of the recording head applied to conventional ink-jet recording apparatuses have the following problems.
When a recording apparatus actually performs a recording operation, in addition to heating for temperature control, a CR (carriage) motor and an LF (line feeding) motor are driven for moving a carriage and an operation for feeding/discharging a recording medium, respectively.
Accordingly, in order to simultaneously perform heating of the recording head to a target temperature within a short time and driving of the CR motor and the LF motor, considerably large electric power is temporarily necessary, resulting in an increase in the required capacity of a power supply and an increase in the cost of the apparatus. On the other hand, in order to reduce power consumption in heating for temperature control, it is necessary to reduce the slope of a temperature rise profile of the recording head, resulting in an increase in the time required for reaching a target temperature and a decrease in throughput.
The present invention has been made in consideration of the above-described problems.
It is an object of the present invention to provide an ink-jet recording apparatus and an ink-temperature control method in the apparatus, in which prompt ink-temperature control can be realized without increasing the capacity of a power supply, and a high-quality image can be recorded.
According to one aspect of the present invention, an ink-jet recording apparatus that performs recording by causing an ink-jet recording head, for performing recording by discharging ink, to perform scanning on a recording medium includes temperature acquisition means for acquiring a temperature of the recording head, heating means, provided within the recording head, for performing temperature control of ink, driving means for driving the heating means in accordance with predetermined parameters, a first motor for causing the recording head to perform scanning, a second motor for conveying the recording medium, driving control means for controlling the driving means in accordance with an output from the temperature detection means, and parameter changing means for changing the parameters of the driving means in accordance with operational states of the first and second motors.
According to another aspect of the present invention, an ink-temperature control method in an ink-jet recording apparatus that performs recording by causing an ink-jet recording head, for performing recording by discharging ink, to perform scanning on a recording medium, including temperature acquisition means for acquiring a temperature of the recording head, heating means, provided within the recording head, for heating ink, driving means for driving the heating means in accordance with predetermined parameters, a first motor for causing the recording head to perform scanning, and a second motor for conveying the recording medium, includes a driving control step of controlling the driving means in accordance with an output from the temperature detection means, and a parameter changing step of changing the parameters of the driving means in accordance with operational states of the first and second motors.
That is, according to the present invention, in an ink-jet recording apparatus that performs recording by causing an ink-jet recording head, for performing recording by discharging ink, to perform scanning on a recording medium, including temperature detection means provided within the recording head, heating means, provided within the recording head, for heating ink, driving means for driving the heating means in accordance with predetermined parameters, a first motor for causing the recording head to perform scanning, and a second motor for conveying the recording medium, the driving means is controlled in accordance with an output from the temperature detection means, and the parameters of the driving means are changed in accordance with operational states of the first and second motors.
According to the above-described configuration, it is possible to change the parameters so that power consumption in the heating means is increased when neither of the first and second motors operates, and power consumption in the heating means is reduced when one of the first and second motors operates, and promptly control the temperature of ink within the range of the capacity of the power supply of the recording apparatus, in accordance with the operational states of the motors.
Accordingly, it is possible to suppress the maximum instantaneous power consumption, promptly control the temperature of ink without increasing the capacity of the power supply, and record a high-quality image by preventing the generation of unevenness in the density due to variations in the amount of ink discharge and incomplete dot shapes due to a failure in ink discharge.
The foregoing and other objects, advantages and features of the present invention will become more apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings.